Health Effects of Household Solid Fuel Use: Findings from 11 Countries within the Prospective Urban and Rural Epidemiology Study.

BACKGROUND: Household air pollution (HAP) from solid fuel use for cooking affects 2.5 billion individuals globally and may contribute substantially to disease burden. However, few prospective studies have assessed the impact of HAP on mortality and cardiorespiratory disease. OBJECTIVES: Our goal was to evaluate associations between HAP and mortality, cardiovascular disease (CVD), and respiratory disease in the prospective urban and rural epidemiology (PURE) study. METHODS: We studied 91,350 adults 35­70 y of age from 467 urban and rural communities in 11 countries (Bangladesh, Brazil, Chile, China, Colombia, India, Pakistan, Philippines, South Africa, Tanzania, and Zimbabwe). After a median follow-up period of 9.1 y, we recorded 6,595 deaths, 5,472 incident cases of CVD (CVD death or nonfatal myocardial infarction, stroke, or heart failure), and 2,436 incident cases of respiratory disease (respiratory death or nonfatal chronic obstructive pulmonary disease, pulmonary tuberculosis, pneumonia, or lung cancer). We used Cox proportional hazards models adjusted for individual, household, and community-level characteristics to compare events for individuals living in households that used solid fuels for cooking to those using electricity or gas. RESULTS: We found that 41.8% of participants lived in households using solid fuels as their primary cooking fuel. Compared with electricity or gas, solid fuel use was associated with fully adjusted hazard ratios of 1.12 (95% CI: 1.04, 1.21) for all-cause mortality, 1.08 (95% CI: 0.99, 1.17) for fatal or nonfatal CVD, 1.14 (95% CI: 1.00, 1.30) for fatal or nonfatal respiratory disease, and 1.12 (95% CI: 1.06, 1.19) for mortality from any cause or the first incidence of a nonfatal cardiorespiratory outcome. Associations persisted in extensive sensitivity analyses, but small differences were observed across study regions and across individual and household characteristics. DISCUSSION: Use of solid fuels for cooking is a risk factor for mortality and cardiorespiratory disease. Continued efforts to replace solid fuels with cleaner alternatives are needed to reduce premature mortality and morbidity in developing countries. https://doi.org/10.1289/EHP3915.

Health effects of household solid fuel use: findings from 11 countries within the prospective urban and rural epidemiology study

Approximately 2.5 billion individuals globally are exposed to household air pollution (HAP) from cooking with solid fuels such as coal, wood, dung, or crop residues (Smith et al. 2014). Concentrations of air pollutants, especially fine particulate matter [PM≤2:5 lminaerodynamicdiameterðPM2:5)], can be several orders of magnitude higher in homes cooking with solid fuels compared with those using clean fuels such as electricity or liquefied petroleum gas (LPG) (Clark et al. 2013; Shupler et al. 2018). PM2:5 in outdoor air has been linked to mortality, Address correspondence to Perry Hystad, School of Public Health and Human Sciences, Oregon State University, Milam Hall 10, 2520 SW Campus Way, Corvallis, OR 97331 USA. Telephone: (541) 737-4829. Email: Perry. hystad@oregonstate.edu SupplementalMaterialisavailableonline(https://doi.org/10.1289/EHP3915). The authors declared hey have no actual or potential competing financial interests. Received 16 May 2018; Revised 16 April 2019; Accepted 16 April 2019; Published 8 May 2019. Note to readers with disabilities: EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact ehponline@niehs.nih.gov. Our staff will work with you to assess and meet your accessibility needs within 3 working days.is chemic heart disease (IHD), stroke, and respiratory diseases (Kim et al. 2015). Despite the large population exposed and the potential for adverse health effects, few prospective cohort studies have examined the health effects of HAP. Only four studies have examined HAP and mortality and reached contradictory conclusions (Alam et al. 2012; Kim et al. 2016; Mitter et al. 2016; Yu et al. 2018). Further, studies have not examined HAP and fatal as well as nonfatal cardiovascular disease (CVD) events. There is growing evidence of the adverse effects of HAP on respiratory diseases and lung cancer; however, most studies are cross sectional or case control in design, with relatively small sample sizes and limited geographic coverage (Gordon et al. 2014). To date, few prospective studies have examined HAP exposures and respiratory events in adults, and the existing studies have reported contradictory findings (Chanetal.2019; Ezzati and Kammen 2001; Mitter et al. 2016). Given the absence of direct epidemiological data, the Global Burden of Disease (GBD) study estimated the potential impact of HAP on health using exposure response relationships that pooled data from studies on outdoor air pollution, secondhand smoke, and active smoking (Burnett et al. 2014). These predictions indicated that 1.6 million deaths were attributable to HAP exposure in 2017, of which 39% were from IHD and stroke and 55% from respiratory outcomes [>90% from chronic obstructive pulmonary disease (COPD) and acute lower respiratory infections (ALRI)] (GBD 2017 Risk Factor Collaborators 2018). Given the lack of direct epidemiological evidence and this large predicted burden, there is an urgent need to directly characterize the health effects associated with HAP. Within the Prospective Urban and Rural Epidemiology (PURE) study, we conducted an analysis of 91,350 adults from 467 urban and rural communities in 11 low to middle-income countries (LMICs) where solid fuels are commonly used for cooking. We examined associations between cooking with solid fuels as a proxy indicator of HAP exposure and cause specific mortality, incident cases of CVD [ CVD death and incidence of nonfatal myocardial infarction (MI), stroke, and heart failure (HF)] and incident cases of respiratory disease [respiratory death, nonfatal COPD, pulmonary tuberculosis (TB), pneumonia, or lung cancer].We estimated associations between solid fuel use for cooking and these outcomes, controlling for extensive individual, household, and community covariates. (AU)

A retrospective cohort study on mortality among silicotic workers in Hong Kong with emphasis on lung cancer / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the relationship between silica or silicosis and lung cancer in a large cohort of silicotic workers in Hong Kong.</p><p><b>METHODS</b>All workers with silicosis in Hong Kong diagnosed between 1981 and 1998 were followed up till the end of 1999 to ascertain their vital status and causes of death, using the corresponding mortality rates of Hong Kong males of the same period as external comparison. Standardized mortality ratios (SMR) for lung cancer and other major causes of death were calculated. Person-year method was used. Axelson's indirect method was performed to adjust for the confounding effect of smoking. Penalized smoothing spline (p-spline) models were used to evaluate the exposure-response relationship between silica dust exposure and lung cancer mortality.</p><p><b>RESULTS</b>A total of 2789 newly diagnosed cases of silicosis were included in the cohort, with an overall 24 992.6 person-years of observations. The loss-to-follow-up rate was only 2.9%. Surface construction workers (51%) and underground caisson workers (37%) constituted the major part of the cohort. There were 853 silicotics observed with an average age at death of 63.8 years. The SMR for all causes and all cancers increased significantly. The leading cause of death was non-malignant respiratory diseases. About 86 deaths were from lung cancer, giving a SMR of 1.69 (95% CI: 1.35 approximately 2.09). The risk of lung cancer death among workers in surface construction, underground caisson, and entire cohort was reduced to 1.12 (95% CI: 0.89 approximately 1.38), 1.09 (95% CI: 0.82 approximately 1.42) and 1.56 (95% CI: 0.98 approximately 2.36) respectively, after indirectly adjusting for smoking.</p><p><b>RESULTS</b>from P-spline model did not show a clear exposure-response relationship between silica dust (CDE and MDC) and lung cancer mortality.</p><p><b>CONCLUSION</b>This cohort study did not show an increased risk of lung cancer mortality among silicotic workers. P-spline model does not support an exposure-response relationship between silica dust exposure and lung cancer mortality.</p>

Study on the interaction under logistic regression modeling / 中华流行病学杂志

When study on epidemiological causation is carried out,logistic regression has been commonly used to estimate the independent effects of risk factors.as well as to examine possible interactions among individual risk factor by adding one or more product terms to the regression model.In logistic or Cox's regression model.the regression coefficient of the product term estimates the interaction on a muhiplicative scale while statistical significance indicates the departure from multiplicativity.Rothman argues that when biologic interaction iS examined,we need to focus on interaction as departure from additivity rather than departure from multiplicativity.He presents three indices to measure interaction on an additive scale or departure from additivity.using logarithmic models such aS logistic or Cox's regression model.In this paper,we use data from a case-control study of female lung cancer in Hong Kong to calculate the regression coefficients and covariance matrix of logistie model in SPSS.We then introduce an Excel spreadsheet set up by Tomas Andersson to calculate the indices of interaction on an additive scale and the corresponding confidence intervals.The results can be used as reference by epidemiologists to assess the biologic interaction between factors.The proposed method is convenient and the Excel spreadsheet is available online for free.

A novel indirect method to adjust for the effects of smoking in occupational epidemiological cohort studies / 中华流行病学杂志

<p><b>OBJECTIVE</b>Previously documented indirect adjustment methods could only adjust for the confounding effects from cigarette smoking. The aim of this paper is to introduce a novel method for dealing with the effects of smoking in occupational, epidemiological cohort studies using a 'smoking adjustment factor'.</p><p><b>METHODS</b>A retrospective cohort study among male silicotic workers purely exposed to silica dusts in Hong Kong (1981 - 1999) was used as an example. 'Smoking adjustment factor' in occupationally exposed smoking and nonsmoking sub-cohorts was expressed as 1/(1- PAR% )xRR and 1/1- PAR% respectively. Relative exposure effect and Synergy index were estimated to assess the multiplicative and additive interactions.</p><p><b>RESULTS</b>'Smoking adjustment factor' for non-smoking and smoking silicotic workers was 1/0.33 and 1/1.62 respectively. Lung cancer standardized mortality ratio(SMR) of all cohort members was reduced from 1.61(95% CI: 1.22-2.10) to 1.08(95% CI:0.81-1.41) after indirectly adjusted for smoking effect. Results from our novel indirect method were in line with that from Axelson' s approach. Relative silicosis effect and synergy index were estimated to be 0.63 (95% CI:0.08-0.79) and 0.90 (95 % CI:0.42-1.94) ,suggesting a significant but negative multiplicative interaction between smoking and silicosis on the risk of lung cancer mortality.</p><p><b>CONCLUSION</b>The merit of this new method was the ability to adjust for the confounding effect and evaluate the interactive effect with smoking. However, comparability of age distribution between occupationally exposed smoking and nonsmoking sub-cohorts was a prerequisite for the accurate estimations of the smoking indirectly adjusted SMR, relative exposure effect, and/or synergy index.</p>